Regulation of the voltage-gated sodium channel Nav1.7 by ubiquitin ligase Nedd4-2

Background and aim: Neuropathic pain (NP) is a frequent and disabling disorder occurring as a consequence of a direct lesion of the nervous system and recurrently associated with a positive shift toward nervous system excitability. Peripheral nerve activity is mainly carried by voltage-gated sodium channels (VGSC), with Nav1.7 isoform being an important candidate since loss of function mutations of its gene is associated with congenital inability to experience pain. Interestingly, ubiquitin ligases from the Nedd4 family are well known proteins that regulate the turnover of many membrane proteins such as VGSC and we showed Nedd2-2 is downregualted in experimental models of chronic pain. The aim of this study was to investigate the importance of Nedd4-2 in the modulation of Nav1.7 at the membrane. Methods: In vitro: whole cell patch clamp on HEK293 cell line stably expressing Nav1.7 was used to record sodium currents (INa), where the peak current of INa reflects the quantity of functional Nav1.7 expressed at the membrane. The possibility that Nedd4-2 modulates the currents was assessed by investigating the effect of its cotransfection on INa. Biotinylation of cell surface was used to isolate membrane-targeted Nav1.7. Furthermore, as the interaction between Nedd4-2 and Nav isoforms was previously reported to rely on an xPPxYx sequence (PY-motif), we mutated this latter to study its impact in the specific interaction between Nav1.7 and Nedd4-2. GST-fusion proteins composed of the Nav1.7 c terminal 66 amino acids (wild-type or PY mutated) and GST were used to pull-down Nedd4-2 from lysates. Results: Co-transfection of Nav1.7 with Nedd4-2 reduced the Nav1.7 current amplitude by ~80% (n = 36, p <0.001), without modifying the biophysical properties of INa. In addition, we show that the quantity of Nav1.7 at the membrane was decreased when Nedd4-2 was present. This effect was dependent on the PY-motif since mutations in this sequence abolished the down-regulatory effect of Nedd4-2. The importance of this motif was further confirmed by pull down experiments since the PY mutant completely eliminate the interaction with Nedd4-2. Perspectives: Altogether, these results point to the importance of Nedd4-2 as a Nav1.7 regulator through cell surface modulation of this sodium channel. Further experiments in freshly dissociated neurons from wild type and Scn1bflox/Nedd4-2Cre mice are needed to confirm in vivo these preliminary data.

Les itinéraires cliniques sont-ils efficaces ? : revue Cochrane pour le praticien

Cet article présente les résultats de la revue systématique: Rotter T, Kinsman L, James E, et al. Clinical pathways : Effects on professional practice, patient outcomes, length of stay and hospital costs. Cochrane Database of Systematic Reviews 2010, Issue 3. Art. No:CD006632. DOI:10.1002/14651858.CD006632.pub2. PMID: 20238347.

Epidemiologie und Behandlung von Brustkrebs im Wallis 2008-2010

Im Rahmen der Zusammenarbeit zwischen dem Walliser Krebsregister (WKR), dem Walliser Gesundheitsobservatorium (WGO) und dem Walliser Departement Onkologie wurde beschlossen, eine Studie über die Epidemiologie und die Behandlung von Brustkrebs im Wallis zwischen 2008 und 2010 durchzuführen. Ziel dieser Studie ist es, die Häufigkeit, die Art der Entdeckung, die Behandlungen sowie die 1- und 2-JahresÜberlebensraten von Brustkrebs im Wallis zu beschreiben. Brustkrebs ist die häufigste Krebserkrankung und die zweithäufigste Krebstodesursache bei den Frauen im Wallis. Zwischen 2008 und 2010 wurden im Wallis 836 Fälle von Brustkrebs diagnostiziert. 90% der Karzinome sind invasiv und 10% in situ. Das Durchschnittsalter bei der Diagnosestellung beträgt 62 Jahre. 10% der Karzinome befinden sich im Stadium 0 (Carcinoma in situ), 38% im Stadium I, 36% im Stadium II, 10% im Stadium III und 4% im Stadium IV. 55% der Fälle werden durch ein individuelles (31%) oder organisiertes (23%) Screening entdeckt. 78% der Fälle werden an einem Tumorboard besprochen.